. Asthma is a costly and widespread breathing disorder prone to strike children. Advances in treatment have led to beta-2 adrenergic drugs, such as terbutaline hemisulfate (TBS), which provide relief with few of the side effects, such as tachycardia, of earlier drugs. Unfortunately, TBS has poor bioavailability by mouth and by inhalation, and neither tablets nor aerosols are ideal for chronic or prophylactic use; inhalation provides temporary protection but does not lend itself to unobtrusive repetitive use, while oral therapy involves several pills a day and may cause tremor. It is asserted that transdermal delivery offers a potentially superior method for both chronic and prophylactic TBS therapy. Ionic drugs such as TBS ordinarily pass through the skin poorly, but recent work has shown that an aqueous isopropanol vehicle can deliver transdermal TBS at rates which should be very adequate for asthma treatment. Phase I will seek to demonstrate the feasibility of this new approach to TBS therapy in in vitro measurements on human skin and in vivo studies in rabbits. Phase II will pursue FDA approval and commercialization of a practical transdermal TBS asthma treatment system.